Segmented electrode structure for quadrature reduction in an integrated device

Abstract

An integrated device includes a MEMS device, such as a gyroscope, having a movable mass spaced apart from a substrate, the movable mass being configured to oscillate in a drive direction relative to the substrate. The integrated device further comprises an integrated circuit (IC) die having a surface coupled with the MEMS device such that the movable mass is interposed between the substrate and the surface of the IC die. An electrode structure is formed on the surface of the IC die, the electrode structure including a plurality of electrode segments vertically spaced apart from the movable mass. Openings extend through the movable mass and the electrode segments overlie the openings. Suitably selected electrode segments can be activated to electrostatically attract the movable mass toward sense electrodes vertically spaced apart from the MEMS to reduce quadrature motion of the movable mass.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates generally to the field of microelectromechanical systems (MEMS). More specifically, the present invention relates to a segmented electrode structure for quadrature reduction in a MEMS-CMOS integrated device.BACKGROUND OF THE INVENTION[0002]Microelectromechanical systems (MEMS) technology has achieved wide popularity in recent years, as it provides a way to make very small mechanical structures and integrate these structures with electrical devices on a single substrate using conventional batch semiconductor processing techniques. One common application of MEMS is the design and manufacture of sensor devices. MEMS sensors are widely used in applications such as automotive, inertial guidance systems, household appliances, game devices, protection systems for a variety of devices, and many other industrial, scientific, and engineering systems. One example of a MEMS sensor is a MEMS angular rate sensor. Alternatively re...

AI Technical Summary

Benefits of technology

The present invention relates to a new electrode structure for a MEMS-IC integrated device that reduces quadrature error in a MEMS sensor. The electrode structure includes a plurality of electrode segments that are connected through routing layers on the IC die to a switch structure and an active circuit. The electrodes can be activated or deactivated to compensate for quadrature motion or bonding misalignments between the IC die and the MEMS device. The invention provides a solution to reduce the impact of quadrature error on the performance of the MEMS sensor.

Problems solved by technology

In vibratory angular rate sensors, an inherent problem is the existence of undesirable interference signals, referred to as a quadrature component or quadrature error.

Unfortunately, quadrature error can result in offset error, reduced dynamic range, and increased noise for the device.

A large quadrature error can even cause a device to rail so that the sense mass comes into contact with conductive electrodes potentially resulting in collision-related damage, such as a short.

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